There are prior art crawler dozers for use in heavy duty applications which have a base machine and a blade apparatus coupled to the base machine. The blade apparatus has a blade configured to push large quantities of soil, sand, rubble, or other material, earthen or otherwise, and a blade driver configured to interconnect the blade and the base machine.
The blade driver has a frame with a pair of push-beams positioned laterally outward from and pivotally coupled to the base machine. The blade is pivotally coupled to the push-beams. The blade driver also has a pitch link in the form of a turnbuckle pivotally coupled to one of the push-beams and the blade and a tilt link in the form of a hydraulic cylinder pivotally coupled to the other push-beam and the blade. The length of the pitch link is adjustable to adjust the pitch of the blade, and the length of the tilt link is adjustable to adjust the tilt or roll angle of the blade (i.e., the angle of the blade about a fore-aft axis of the dozer). When the pitch link is lengthened, a corresponding amount of tilt angle adjustability is lost since lengthening of the pitch link causes the rod of the tilt link to extend correspondingly.
One type of prior art blade driver has a link anchor on each of the two push-beams: one link anchor for anchoring a frame end of the pitch link and one link anchor for anchoring a frame end of the tilt link. Each such link anchor includes a plurality of mounting points (three) for the respective link, each mounting point having a pair of holes for receiving a pin coupled to the frame end of that link. The mounting points of the two anchors are arranged in pairs, one from the pitch link anchor and one from the tilt link anchor, such that each pair of mounting points corresponds to a respective pitch of the blade relative to the frame. The frame ends of the pitch and tilt links are thus coupleable to any one of the pairs of mounting points to establish the blade at the pitch corresponding to that pair of mounting points, without causing a loss of tilt angle adjustability. As is known in the prior art, dozer operators have complained about the limitations of the pitch adjustability of such an arrangement due to its coarse pitch resolution.